#### Transcript of Archimedes' Principle

Archimedes' Principle

Density

Water Displacement

Buoyancy

**Archimedes' Principle**

**The Law of Buoyancy**

"The buoyant force acting on a submerged or floating object is equal to the weight of the displaced fluid."

the buoyant force = the weight of the displaced water

Buoyant Force

- the tendency of a body to float or to rise when submerged in a fluid

where P = pressure

A = area

- the amount of an object (weight or mass) there is an a given volume (the amount of water the object displaces).

Water (H2O) = 1g/cm³ or 1000kg/m³

1 g =1 cm³ = 1 mL

- simply when something (e.g. a block) is put into water, and the water level rises.

V2-V1

Problem #1

You have a block of a mystery material, 12 m long, 11 m wide and 3.5 m thick. Its mass is 1155 grams.

Principle of Floatation

If density of the object = density of liquid, buoyant force = weight of the object: it will float

If density of the object > density of liquid, buoyant force < weight of the object: it will sink

submerged volume/total volume = density of object/density of liquid

Problem #2

What percentage of the volume of ice is submerged water? Ice has a density of 900 kg/m³.

Specific Gravity Determination

It is the ratio of density of substance to the density of water.

specific gravity = Wa/Wa-Ww

for liquid:

specific gravity = Wa- WL/Wa-Ww

Problem #3

A stone is found to weigh 6.2 N in air, 4.5 in water, and 5.3 N in an unknown liquid. Find the density of the stone and unknown liquid.

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